Laser-Compressed Plastic Turns Into Ultra-Pure Nanodiamonds

Materials Science · Nanotechnology

They were trying to recreate the crushing pressure inside Neptune. What they got, almost by accident, was a cleaner way to make diamonds.

Three laser shots a minute, a sheet of ordinary plastic, and diamonds fired out the back end faster than a meteorite.

A laser shock wave compresses ordinary plastic film into diamond, ejecting the particles at speeds comparable to a meteorite impact.

Scientists Simulating Neptune's Core Found a New Way to Mass-Produce Diamonds

Nanodiamonds are exactly what they sound like: diamond particles measured in millionths of a millimeter, extremely hard, stable, and heat-resistant.

That combination makes them useful across medicine, new materials, catalysis, and energy technology — but producing them cleanly and consistently has always been a genuine bottleneck.

Researchers at the Helmholtz-Zentrum Dresden-Rossendorf and the University of Rostock weren't originally trying to solve that problem at all.

They were firing high-power lasers at plastic to simulate the extreme pressure and heat found deep inside ice giant planets like Neptune and Uranus.

Dominik Kraus, founding director of HZDR's new HEDI—Institute of High Energy Density Physics, put the reaction to the early results plainly: what surprised us, however, was how quickly it happened.

That speed is what turned a planetary physics curiosity into a materials science opportunity, now published in the journal Diamond and Related Materials.

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Why Simulating a Planet's Interior Makes Diamonds

Deep inside planets like Neptune and Uranus, temperatures reach several thousand degrees Celsius, while pressures climb to millions of times what we experience in Earth's atmosphere.

Recreating those conditions in a lab, even briefly, is genuinely difficult — which is precisely why researchers turn to high-power lasers to do it.

Earlier work had already shown diamonds could form this way, but only briefly, under conditions that vanished the instant the experiment ended.

What hadn't been demonstrated was whether those diamonds could actually survive the transition back down to normal pressure and temperature — the step that separates a physics curiosity from a usable material.

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The Machine: Firing Lasers at Plastic Film

The experiments took place at the Extreme Light Infrastructure, a specialized laser facility south of Prague known for combining very high energy with a genuinely high repetition rate.

Three times per minute, the facility's L4n-P3 laser fires pulses at a 100-micrometer-thin sheet of PET plastic film, systematically raster-scanning across its surface shot by shot.

Each pulse triggers a powerful shock wave that compresses the plastic to pressures around 100 gigapascals — hundreds of thousands of times normal atmospheric pressure.

Nanodiamonds form directly inside that shock wave, a process that happens and completes in an astonishingly short window of time.

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Catching a Diamond Moving Faster Than a Bullet

Making the diamonds turned out to be only half the engineering problem. Collecting them intact was the other half.

Kraus describes exactly what happens as the compression wave finishes its work: it abruptly hits the vacuum at the edge of the sample, accelerating the newly formed nanodiamonds to more than 10 kilometers per second.

That's genuinely comparable to the speed of a meteorite impact — fast enough that slamming into an ordinary hard surface would simply destroy the diamonds the instant they were made.

To solve that, the researchers needed an unusually soft landing. They settled on a vacuum-compatible, water-soluble ionic gel as the collection medium, gentle enough to absorb the impact without shattering the particles.

Each single shot ejects roughly 10 trillion nanometer-scale diamonds of remarkably uniform size directly into that collection cylinder.

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Seeing Individual Atoms in a Speck of Plastic-Turned-Diamond

Ten trillion diamonds sounds enormous, but at these dimensions, it adds up to almost nothing by weight.

Each nanodiamond averages about three billionths of a meter across, built from roughly 3,000 carbon atoms — genuinely tiny, even by nanotechnology standards.

That small yield was still enough to examine directly using the ELMI-MV electron microscope at the University of Rostock, an instrument capable of resolving individual atoms.

Ben Heuser of HZDR, the study's primary author, who ran the experiments as part of his doctoral thesis, described finally seeing the diamonds this clearly: that was a special moment we had been working toward for years.

That direct atomic-level confirmation is what turns "we think we made diamonds" into a genuinely verified result.

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From Polishing Grit to Quantum Sensors

Nanodiamonds aren't a hypothetical material waiting for a use case — they already have one, in grinding and polishing agents used across manufacturing today.

The laser-compression method's real advantage is precision: smaller, cleaner, more tightly controlled particle sizes than explosion-based production can reliably deliver.

Because these diamonds come from plastic, they can also be doped with foreign atoms relatively easily, tuning them for specific purposes — including potentially better contrast agents for medical MRI scans.

Smaller diamonds also offer a larger combined surface area, which matters directly for catalysis — including splitting CO₂ using sunlight, a genuinely useful application for climate-relevant chemistry.

Looking further out, researchers expect these particles to serve as highly sensitive quantum sensors, a role where their precise, controllable structure becomes a real technical advantage.

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Chasing an Even Stranger Form of Carbon

Nanodiamonds aren't actually the most ambitious target this process is now aimed at.

The team wants to use the same laser-compression approach to create BC8, an exotic form of carbon that had previously existed only as a theoretical prediction.

BC8 is denser than diamond and similarly hard, but notably less brittle — a genuinely unusual combination of properties for a carbon-based material.

It doesn't occur naturally anywhere on Earth, because the planet simply doesn't produce the extreme conditions needed to form it outside a laboratory like this one.

Using even higher pressures than those used for nanodiamonds, the researchers plan to attempt producing BC8 directly from plastic, with an initial experiment scheduled for November.

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Manohar Insight

What I like most about this story is how honestly it represents how applied science actually happens — sideways, not in a straight line from question to answer.

Nobody set out to build a better diamond factory. They set out to understand what's happening inside Neptune, and the diamond factory showed up as a byproduct of paying close attention to the results.

The engineering detail I'd point to as genuinely clever is the collection method. A meteorite-speed impact problem, solved with something as unglamorous as a soft, water-soluble gel — that's applied physics at its most practical.

The yield numbers are the honest caveat here. A few hundred micrograms from 100 shots is a proof of concept, not a production line, and getting to milligram-scale output is real, unfinished work.

But the scalability argument is genuinely credible, precisely because it's riding on unrelated investment: fusion research is already pushing high-repetition-rate lasers forward for entirely different reasons.

I'd watch the BC8 experiment closely. A material that's existed only in theory becoming physically real, from plastic, would be the bigger story hiding just behind this one.

The real achievement here isn't that lasers can make diamonds. It's that studying a planet nobody's ever visited taught scientists something genuinely useful about the material sitting in a plastic bottle.